1. Field of the Invention
This invention relates to wireless local area networks (wireless networks), and, more particularly, to a system for real traffic replay over wireless networks.
2. Description of Related Art
Real traffic replay is highly applied in wired networks over the last decade. The packet exchanges with the device under test (DUT) should be precisely controlled following the protocol specification. However, traffic replay in wireless networks suffers further challenges due to variant wireless environments. Because a wireless medium is open and shared, transmissions may suffer packet errors caused by fading, noise, and interference. Therefore, traffic behaviors could be disturbed by environment effects. Even though the environment effects could be reproduced, poor coordination between the packet-replay control and environment emulation may result in inconsistent environment effects to packets. As a result, to apply real traffic replay in wireless networks requires not only packet-replay control but also environment emulation coordinately.
Compared to the packet traces record in the real environment, the reproduced traffic may suffer false negative (FN) and false positive (FP). FN indicates a successful packet exchange in the real environment fails in traffic replay. On the contrary, FP indicates a failed packet exchange in the real environment succeeds in traffic replay. Lack of packet-replay control, or environment emulation, or coordination between them may result in FN and FP cases.
In FIG. 1A, due to loss of packet-replay control, the ACK from Node A to Node B is transmitted in advance. The first and third Directed Data suffer FP and FN, respectively. Transmissions in wireless networks are prone to bit errors due to variant environments. In FIG. 1B, the first Directed Data intends to suffer FP because the noise disturbing the first Directed Data is not reproduced and the packet error rate decreases. In contrast, the second Directed Data encounters the unexpected noise due to lack of environment emulation. The FN case might occur. Even though the packet-replay control and environment emulation is applied, the poor coordination between them can also result in FN or FP cases. FIG. 1C shows that the reproduced noise with an uncontrolled duration could lead the second Directed Data to the FP case and the second Probe Req. to the FN case.
The above examples illustrate that lack of packet-replay control or environment emulation may highly affect the traffic behaviors. Therefore, both of the packet-replay control and environment emulation should be reproduced coordinately.